A variable is a temporary memory location that holds its data temporarily. C requires the data type of the variable to be well defined at the time of variable declaration, according on its value.
Syntax:
data_type variable_list;
Rules for using C Variables:
- C Variable name starts with a letter or underscore only; numbers and special characters are restricted for this.
- C Variables name can contain alphanumeric characters and underscores only.
- C Variables name can not contain any white space within it.
- C Variables name should not be same as any reserved word or keyword already defined in C library.
C Variables Types:
C Variable are classified according to the scope of the variable inside the code, i.e, the portion of the script where the variable can be used. These are:
Local:
Local Variables can only be accessed within the function where it is declared.
Global:
Global Variables can only be declared outside the function and can be accessed by all the functions.
Static:
Static Variables are declared with static keyword for a variable to retain its value between multiple function calls.
External:
External Variables are declared with extern keyword for a variable to be shared in multiple files.
Automatic:
Automatic Variables can be declared with auto keyword. Although, every variable declared inside a function, by default, are automatic variables.
Example 1: Local declaration of Variables.
#include<stdio.h> void main() { int a, b; printf ("Enter two numbers: "); scanf ("%d, %d",&a,&b); printf("Sum of x+y = %i", a+b); } |
Output
Enter two numbers: 2,3 Sum of x+y = 5 |
Example 2: Global declaration of Variables.
#include<stdio.h> int sum; void main() { int a, b; printf ("Enter two numbers: "); scanf ("%d, %d",&a,&b); sum = a+b; printf("Sum of x+y = %i", sum); } |
Output
Enter two numbers: 2,3 Sum of x+y = 5 |
